(Fortune) -- What do Oreo cookies made by Nabisco (KFT, Fortune
500), Cheez-It crackers from Kellogg's (K, Fortune 500) or General
Mills' (GIS, Fortune 500) Fiber One Chewy Bars have to do with global
warming and the destruction of tropical rainforests? A lot, say
environmental activists.

The link between the supermarket shelf, climate change and shrinking
rainforests is palm oil, a controversial ingredient that may now be the
most widely-traded vegetable oil in the world.

Here's the problem: Demand for palm oil, which is found in soaps and
cosmetics as well as food, has more than doubled in the last decade as
worldwide food consumption has soared. Farmers, in turn, are expanding
their plantations, burning forests in Indonesia and Malaysia, where
nearly all of the palm oil imported to the United States originates.
Deforestation is the primary reason that Indonesia's greenhouse gas
emissions are the third-highest in the world.

The Rainforest Action Network, Greenpeace International, Friends of
the Earth and the Center for Science in the Public Interest are all
campaigning against palm oil. (You can find their arguments here and here and here and here.)
Last week, RAN asked about 2,000 volunteers to sneak into food stores
across the United States and attach stickers to products made with palm
oil.